Color photography and cinematography



Patented June 19, 1934 PATENT OFFICE 1,963,197 COLOR PHOTOGRAPHY AND CINEMATOG- RAPHY Alfred Froehlich, Dessau in Anhalt, Germany, assignor to Agfa Ansco Corporation, Binghamton, N. Y., a corporation of New York No Drawing. Application May 16, 1932, Serial 8 Claims.v

formula bk- Na are very sparingly soluble in water. By shaking, for instance, silver chloride with a diazotate solution, the silver compound can be converted into silver diazotate, chlorine ions passing into solution.

This observation leads to the preparation of dyestuif pictures from'pictures composed of a finely divided metal, more particularly silver pictures, produced in the usual photographic manner. The process of this invention consists in bleaching out, for instance, a silver picture to silver chloride by means of a solution of copper chloride or the like, treating the latter for some minutes with a solution of a soluble antidiazotate, alkali compounds being specially suitable to this end, washing out the excess of diazotate with water and coupling the silver diazotate which has been produced in the picture layer with an azo dyestuff component to obtain an azo dyestuff of the shade desired in each special case.

The coupling process may be carried out in an acid or in an alkaline medium. Whereas it is realized very easily in an acid solution, it is adin an alkaline medium, by heat and to use a previouslyhardened picture layer. After coupling the picture is washed for some minutes with water, whereafter the silver or silver salt which separates in the coupling process and may still be present in the layer is extracted, in the usual manner, by means of a fixing bath or a solvent for the silver or salts thereof, so that a pure azo dyestufi picture is produced.

According to the process of this invention it is possible to obtain, by a suitable selection of the components, any desired tint, and particularly to produce the dyes which are best suited for purposes of the twoand three-color photography or cinematography. For the preparation of a, twovisable to accelerate the process, when workingv In Germany May 16, 1931 or three-color picture, the picture layers must be arranged on transparent or translucent supports, particularly on such as are made of a cellulose ester or regenerated cellulose, and the part-color pictures produced by printing the different partcolor negatives according to the process described are brought into register as strictly as possible. If required, several picture layers may be arranged on a single support one over the other or on the two faces of the support, so that after 65 printing it is not necessary to bring the part-pictures into registration. It is likewise possible to produce color pictures on an opaque support, for instance on paper. These pictures are viewed by reflected light.

Suitable antidiazotates are, for instance, those of para-nitraniline, B-naphthylamine, benzidine, dianisidine, para-aminoazobenzene and a great many other compounds. As coupling components all components customary in the technique of manufacturing azo dyestuffs are suitable; those yielding dyestuffs insoluble in water are, however, preferred because the pictures produced. thereby are particularly sharp. If the'dyes are not sufficiently insoluble, their dissolution is prevented by adding to the solution containing the coupling component an agent having a saltingout action.

Coupling components which do not interact with or are not dissolved by photographic developing and fixing baths, may be incorporated in the metal halide emulsion more particularly the silver halide emulsion at some stage of the production of the emulsion. In this case it is possible to cover the support with-superimposed layers of silver salt emulsions, containing difierent coupling components. If two coupling components are selected which form with the same diazo component in the one case ayellow and in the other case a purple dyestufl, it is possible to produce, by the use of suitably sensitized emulsions, on the one face of a support the yellow and the red part-picture, whereas the blue part-picture is produced on the other face of the support in a similar manner by means of a blue-coupling component. If during the coupling process a temperature higher than ordinary is used, the gelatin of the photographic layer is preferably hardened by means of formaldehyde or any other suitable hardening agent. The gelatin can be hardened at any stage in the production of the picture, but the hardening must precede the coupling process, thus the gelatin can be treated with a hardening agent during the production of the light-sensitive emulsion layer or after the picture composed of finely divided metal has been I produced.

The following examples illustrate the invention:

Example 1.A silver positive bleached out to silver chloride is placed for 10 minutes in a filtered solution of 1 gram of a-naphthalene-sodium-antidiazotate dissolved in 100 cc. of water and containing an addition of a few drops of caustic soda solution and is then washed for 45 minutes in running water. The picture now consists of a-naphthalene-silver-antidiazotate, while the whites are free from diazotate. The picture is then immersed for 5 minutes in a solution of 2 per cent. strength of LB-diamino-naphthalene in sulfuric acid of 1% per cent. strength,and washed with water. This operation may be followed, if desired, by a treatment in a thiosulfate bath in order to accelerate the dissolution of the silver sulfate produced during the reaction, and by an after-treatment in water which has been slightly acidified. The picture obtained is blue.

Example 2..A silver picture bleached out to silver chloride in gelatin hardened by means of formaldehyde is immersed for 10 minutes in a saturated solution of the antidiazotate of dianisidine which has been mixed with a small amount of caustic soda solution and filtered, and is then Washed with water for one hour. For coupling,

the picture is treated with a solution of 1 per cent. strength of H-acid v(1-amino-8-naphthol- 3.6-disulfonic acid) heated to C. After 1 to 1 minutes the coupling process is complete. The picture is then well washed, the silver or silver oxide which has been formed is bleached to silver chloride in a solution of cupric chloride, the silver chloride is dissolved in thiosulfate solution, and the picture is washed and subsequently bathed in slightly acidified water. The picture obtained is likewise blue.

Example 3.A silver chloride picture prepared according to Example 2 is bathed for 10 minutes in a solution of l per cent. strength of a-naphthalene-antidiazotate which has been mixed with a small quantity of caustic soda solution and filtered; the picture is then rinsed with water and immersed for about 1 minute in a solution of 1 per cent. strength of H-acid of 70 C. The picture is washed in a solution of 2 per cent. strength of potash alum. The bleaching and fixing baths according to Example 2 must also be mixed with potash alum in order to prevent bleeding. The picture obtained is-red.

Example 4.A picture of a-n'aphthalene-silverantidiazotate, prepared according to Example 3, is coupled with a resorcinol solution of 1 per cent.

- strength at 70 C. which has been saturated with sodium chloride. The picture is washed for a short time, bleached with cupric chloride, fixed and washed again. The picture obtained is yellow.

Example 5.-The silver diazotate picture, prepared according to Example 3 is bathed for 5 minutes in an anthranilic acid solution contain ing sodium bicarbonate, and then dried. Coupling is effected by exposure for 2 minutes in a current of steam charged with a small amount of acetic acid. Then the picture is rinsed with water and fixed; it is orange.

Example 6.-The silver picture is converted, according to any of the known methods, into a silver halide picture and well rinsed with water. It is then bathed for 10 minutes in a saturated solution of a-naphthalene-sodium-antidiazotate, filtered, and mixed with some drops of caustic soda solution. The picture is then rinsed with water for 1 hour. For coupling, the picture is dipped into a solution of 1-amino-8-naphthol- 2.4-disulfonic acid to which some drops of acetic acid have been added. When operating at a temperature of 40 C. the coupling process is complete after l'minute. After bleaching and fixing again a purple-red picture is obtained.

Ewample 7 3.2 grams of fl-naphthylamine are dissolved in alcohol to form a concentrated solution. The solution is added to 30 cc. of silver halide emulsion and the mixture cast on a plate of the size 18 x 24 cm. After exposure the plate is developed in the usual manner, fixed in a neutral fixing bath, washed, and bleached with a 2 per cent. solution of copper chloride. After having been washed, the plate is bathed for about 5 minutes in a cold solution of fl-naphthylsodium-antidiazotate which has been made alkaline by a caustic alkali. Hereafter the plate is washed for about 30 minutes and the. coupling process which sets in during this operation carried to an end in an acetic acid of 2 per cent. strength. After washing a red transparent diazo picture is obtained having clear whites.

What I claim is:

1. A dye-toning-process which comprises exposing to light a photographic material provided with an emulsion layer containing a light-sensie tive silver halide, said silver being capable of forming a difiicultly soluble diazotate, developing said exposed material, bleaching out the picture obtained and composed of finely divided silver, reacting on said bleached out picture with a diazotate, and treating the formed diazotate with a coupling compound.

2. A dye-toning-process which comprises exposing to light a photographic material provided with an emulsion layer containing a light-sensitive silver halide, said silver being capable of forming a difiicultly soluble diazotate and .a coupling compound, said coupling compound being not affected by the photographic developing baths, developing said exposed material, bleaching out the picture obtained composed of finely divided silver, reacting on said bleached out picture with a diazotate, and causing said coupling compound contained in the emulsion to interact with the formed diazotate.

3. A dye-toning-process which comprises exposing to light a photographic material provided with an emulsion layer containing a silver halide, developing said exposed material, bleaching out the silver picture obtained, reacting on said bleached out picture with an antidiazotate, and treating the formed silver antidiazotate with a coupling compound.

4. A dye-toning-process which comprises exposing to light a photographic material provided with an emulsion layer containing a silver halide and a coupling compound, said coupling compound being not affected by the photographic developing baths, developing said exposed material, bleaching out the silver picture obtained, reacting on said bleached out picture with an antidiazotate and causing said coupling compound contained in the emulsion to interact with the formed silver antidiazotate.

5. A dye-toning-process which comprises exwith several emulsion layers containing a silver halide and each layer being provided with a different coupling compound, said coupling compounds being not affected by the photographic developing baths, developing said exposed material, bleaching out the silver pictures obtained, reacting on said bleached out pictures with an antidiazotate and causing said coupling compounds contained in the difierent emulsion layers to interact with the formed silver antidiazotates.

6. A dye-toning-process which comprises exposing to light a photographic material provided with an emulsion layer containing a silver halide, developing said exposed material, bleaching out the silver picture obtained, reacting on said bleached out silver picture for 10 minutes with a solution of 1 gram of a-naphthalene-sodiumantidiazotate in 100 cc. of water and.containing an addition of some drops of caustic soda solution, washing the formed silver diazotate and treating the diazotate for 5 minutes with a 2 per cent. solution of l.8diaminonaphthalene in sulfuric acid of 1 per cent strength.

7. A dye-toning-process which comprises exposing to light a photographic material provided with an emulsion layer containing a silver halide,

developing said exposed, material, treating the silver picture obtained with a hardening agent, bleaching out the silver picture contained in the hardened gelatin, bathing said bleached out picture in a saturated solution of the antidiazotate of dianisidine to which a small amount of caustic soda solution has been added, washing the formedreacting on said bleached out picture with B- naphthyl-sodium-antidiazotate, and causing said fi-naphthylamine contained in the emulsion to interact with the formed silver antidiazotate.

ALFRED FROEHLICH. 

